1. Field of the Invention
The present invention relates to a plane type displaying apparatus equipped with an electric field emitting type cathode.
2. Description of the Related Art
In the following will be explained a conventional example of a plane type displaying apparatus equipped with a field emitting type cathode (emitter) with reference to FIG. 1 and FIG. 2. In FIG. 1 and FIG. 2, KK and G are respectively a plurality of cathode electrodes and gate electrodes (drawer electrode) of an equal width and an equal space forming an XY matrix and disposed like crossing and opposing each other through insulating layers Z. A is an anode electrode opposing the plurality of gate electrodes G at a predetermined space. A fluorescent substance layer P is coated on a surface (a lower surface is permissible) of the anode electrode A.
At crossing portions between the plurality of cathode electrodes KK and the plurality of gate electrodes G, circular holes H are bored and at the same time, cavities CV are provided to be connected with the holes H in the insulating layer Z. In the cavities CV, conic shape Spindt type field emission type cathodes (emitter) K are planted on the cathode electrode KK. The field emitter type cathode K is comprised of Mo, W, Cr or the like which will emit an electron by way of a tunnel effect when selectively applying an electric field of about 0.01V/xc3x85xcx9c0, 1V/xc3x85 thereto. Then, a positional relationship between the hole H and the cathode K is set so that a vertex of the cathode K is positioned at a center of the aperture H.
These electrodes G, cathode electrodes KK, cathodes K, anode electrode A, fluorescent substance layer P and insulating layer Z are accommodated in a flat tube formed of glass and the like and the inside of the flat tube is made a vacuum. A fixed voltage, for example, a direct current voltage of 3 kV is applied to the anode electrode A. A direct current voltage of, for example, 100V from a scan driver SD is, in FIG. 1, successively and cyclically applied to the plurality of gate electrodes G from the upper side gate electrode G to the lower side gate electrode G. A voltage of 0V (for example, a voltage of 0Vxcx9c10V is permissible) in response to an image signal is selectively applied to the plurality of cathode electrodes KK from the data driver DD.
As a result, at the crossing point between the gate electrode G to which the direct current voltage of 100V is applied and the cathode electrode KK to which the voltage of 0V is applied out of the plurality of gate electrodes G and the plurality of cathode electrodes KK, electric field emission (i.e., emissions of electrons) is started between the cathode K and the anode electrode A and an electron drawn out from the cathode K is bombarded on the anode electrode A by the gate electrode G, thereby resulting in luminescence of the fluorescent substance layer P.
In the plane type displaying apparatus, an image is displayed by collection of as one pixel, for example, 1000 pieces of the crossing points between the gate electrode G and the cathode electrode KK as one pixel. When the whole of fluorescent substance layer P is comprised of a white luminescing fluorescent substance layer, a monochrome plane type displaying apparatus can be obtained while when the fluorescent substance layer P is comprised of red, green and blue luminescing fluorescent substance stripes, each having a width of one pixel, a color plane type displaying apparatus can be obtained.
As for an example of the electric field emitting type A cathode (emitter) K, there are various kinds other than what is shown in FIG. 2 and one example of a part thereof will be explained with reference to FIG. 3. Meanwhile, A1, B1, C1 of FIG.3 are plan views of the cathodes and A2, B2, C2 of FIG.3 are cross-section views of the cathodes in A1, B1, C1 of FIG.3 respectively.
A1, A2 of FIG.3 show a pair of electrodes with one thereof being the cathode while the other being the gate electrode, and from an end portion of the cathode opposing the gate electrode, the electron is emitted to the anode electrode to be emitted graphically.
B1, B2 of FIG.3 show, for example, a cathode having a square aperture and the electron is emitted from an edge of the square aperture.
C1, C2 of FIG.3 show a concave cathode with a disc surface being a curve surface like forming, for example, a spherical surface and the electron is emitted from an edge of the concave.
As for an example of the electric field type emitting to cathode or emitter K, it may be formed of an MIM type electron emitting element which consists of metal/insulating layer/metal.
In the plane type displaying apparatus explained with respect to FIG. 1 and FIG. 2, presence or absence of discharge luminescence is carried out by presence or absence of application of respective predetermined voltages to the cathode (emitter) and the gate electrode (drawer electrode). Therefore, since it is necessary to apply a strong electric field (for example, 0.05V/xc3x85) to the cathode forming a selected pixel every time the pixel is selected, that is, control of the electron emission at a time of selection/non-selection of the pixel is carried out by the electric field, a driving voltage becomes high when the pixel is selected, thereby incurring a problem in respect to a high speed operation as well as power consumption.
In view of such points, the present invention is, a type of displaying apparatus having a plurality of electric field emitting type cathodes and a fluorescent substance layer which is made to brighten by bombarding of the electron emitted from of the electric field emitting type cathode selected from among the plurality of electric field emitting type cathodes, to provide a plane type displaying apparatus which can lower a driving voltage for having the plurality of electric field type cathode selectively emit the electron, reduce the power consumption as well as perform the high speed operation.
Also, the present invention is in the plane type displaying apparatus having an electric emitting type cathode group wherein pixels, each of them consisting of electric field emitting type cathodes disposed in a matrix of m rows by n columns (however, m, n are integers equal to or larger than 1) are disposed in a matrix of M rows by N columns (however, M, N are integers equal to or larger than 2) and a fluorescent substance layer made to brighten by bombarding of the electron emitted from the electric field emitting type cathode at every pixel in the electric field emitting type cathode group, to provide a plane type displaying apparatus which can lower the driving voltage for having the electric field type cathodes group selectively emit the electron at every pixel, reduce the power consumption as well as perform the high speed operation.
A plane type displaying apparatus according to a first present invention comprises a plurality of electric field emitting type cathodes, a high-tension electrode which fixedly gives a strong electric field forming a Schottky barrier capable of making possible emitting electrons from the plurality of electric field emitting type cathodes to a surface of the plurality of electric field emitting type cathodes, a two dimensional MOS gate array which is connected to the plurality of electric field emitting type cathodes and controls presence or absence of the electron emission from the plurality of electric field emitting type cathodes, and a fluorescent substance layer made to brighten by bombarding of the electrons selectively emitted from among the plurality of electric field emitting type cathodes.
According to the first present invention, the high tension electrode fixedly gives the strong electric field forming the Schottky barrier capable of making possible the electron emission from the plurality of electric field type cathodes to the surfaces of the plurality of electric field type cathodes, the two-dimensional MOS gate array controls the presence or absence of the electron emission from the plurality of electric field type cathodes and the fluorescent substance layer is made to brighten by the bombarding of the electrons selectively emitted from among the plurality of electric field type cathodes.